Variability of broad absorption lines in a QSO SDSS J022844.09+000217.0 on multi-year timescales

TL;DR

This study analyzes multi-year spectroscopic data of a quasar to understand the variability of broad absorption lines, revealing correlations with spectral index and luminosity, and suggesting dust's role in outflows.

Contribution

It provides the first detailed multi-epoch analysis of BAL variability in SDSS J022844.09+000217.0, highlighting the role of dust and outflows in BAL dynamics.

Findings

Strong correlation between BAL EW and spectral index.

Weak negative correlation between BAL EW and luminosity.

BAL variability not primarily driven by photoionization.

Abstract

The variability of the broad absorption lines is investigated for a broad absorption line (BAL) QSO, SDSS J022844.09+000217.0 (z = 2.719), with 18 SDSS/BOSS spectra covering 4128 days in the observed frame. With the ratio of the rms spectrum to the mean spectrum, the relative flux change of the BAL-trough is larger than that of the emission lines and the continuum. Fitting the power-law continuum and the emission line profiles of \civ $\lambda$1549 and \siiv$\lambda$1399, we calculate the equivalent width (EW) for different epochs, as well as the continuum luminosity and the spectral index. It is found that there is a strong correlation between the BAL-trough EW and the spectral index, and a weak negative correlation between the BAL-trough EW and the continuum luminosity. The strong correlation between the BAL-trough EW and the spectral index for this one QSO suggests that dust is intrinsic to outflows. The weak correlation between the BAL variability and the continuum luminosity for this one QSO implies that the BAL-trough variation is not dominated by photoionization.